Manufacturing method of a sliding bearing

ABSTRACT

This sliding bearing comprises a pair of semicircular half bearings formed into a cylindrical shape by bringing both circumferential ends thereof into contact with each other. The axial width of the half bearings is narrower in both circumferential ends and the circumferential center, and wider in the quarter parts located therebetween. During manufacturing of the half bearings, finishing by cutting processing is first performed on the parts of a flat-plate material which after formation are to become the two axial-direction end faces and the two circumferential-direction end faces of the half bearings, and thereafter, the flat-plate material is deformed into a semicircle.

CROSS REFERENCE TO RELATED APPLICATIONS

This is the U.S. national stage of application No. PCT/JP2013/070456,filed on Jul. 29, 2013. Priority under 35 U.S.C. § 119(a) and 35 U.S.C.§365(b) is claimed from Japanese Application No. 2012-171284, filed Aug.1, 2012, the disclosure of which is also incorporated herein byreference.

DESCRIPTION

TECHNICAL FIELD

The present invention relates to a sliding bearing and a manufacturingmethod thereof. In detail, the present invention relates to a slidingbearing that both peripheral ends of a pair of semicircular halfbearings are contacted to each other so as to be formed cylindrically,and a manufacturing method thereof.

BACKGROUND ART

Conventionally, a sliding bearing that peripheral ends of a pair ofsemicircular half bearings are contacted to each other so as to beformed cylindrically is known (Patent Literature 1). In the case ofmanufacturing such a sliding bearing, a flat-plate material is deformedsemicircular by press shaping, and subsequently, end surfaces of bothaxial ends and both peripheral ends of the semicircular material are cutso that a lateral width of the half bearing is made uniform andso-called finishing processing is performed.

PRIOR ART REFERENCE Patent Literature

Patent Literature 1: the Japanese Patent Laid Open Gazette 2011-179572

DISCLOSURE OF INVENTION Problems to Be Solved by the Invention

Herein, in the sliding bearing of an engine for a car, magnitude of loadapplied to the sliding bearing from a rotating crankshaft is changed ineach of parts along an axial direction corresponding to timing ofexplosion in a combustion chamber, and especially large load is appliedto quarter parts positioned between both peripheral ends and aperipheral central part.

In contrast, in the conventional half bearing, since the width in theaxial direction is uniform, the width must be set corresponding to theparts to which the large load is applied, whereby the width of theperipheral ends and the central part to which the large load is notapplied is larger than a required width.

As a result, frictional resistance with the crankshaft caused by thelarge width is generated excessively at the peripheral ends and thecentral part, whereby problems such as deterioration of fuel efficiencyare caused.

On the other hand, in a conventional manufacturing device of the slidingbearing, the flat-plate material is deformed semicircular and thenfinished by cutting processing, whereby it is difficult to change thewidth in the axial direction in each of parts.

In consideration of the above problems, the present invention provides asliding bearing having suitable width in an axial directioncorresponding to positons to which load is applied, and provides amanufacturing method which can manufacture the sliding bearing.

MEANS FOR SOLVING THE PROBLEMS

According to the invention of claim 1, in a sliding bearing formedcylindrically by engaging both peripheral ends of a pair of semicircularhalf bearings with each other, an axial width of the half bearings issmall in both peripheral ends and a peripheral central part and is largein a quarter part positioned therebetween, and end surfaces of bothaxial ends of the half bearings are finished by cutting processing.

According to the invention of claim 2, in a manufacturing method of asliding bearing wherein flat-plate materials are deformed semicircularso as to manufacture semicircular half bearings and both peripheral endsof the half bearings are contacted to each other so as to shape thesemembers cylindrically, parts of the flat-plate materials which are to beboth axial end surfaces and both peripheral end surfaces of the halfbearings after the deformation are finished by cutting processingpreviously, and subsequently, the flat-plate materials are deformedsemicircular so as to manufacture the half bearings.

EFFECT OF THE INVENTION

According to the invention of claim 1, the quarter part to which largeload is applied from the crankshaft is wide and the peripheral ends andthe peripheral central part to which large load is not applied arenarrow, whereby sliding resistance of these narrow parts can be reducedso as to improve fuel efficiency.

The end surfaces of the axial ends of the half bearings are finished bythe cutting processing, whereby the present invention can use thesliding bearing having suitable axial width with the positions to whichloads are applied.

According to the invention of claim 2, before the flat-plate materialsare deformed semicircular, the parts of the flat-plate materials whichare to be both axial end surfaces and both peripheral end surfaces ofthe half bearings are finished by the cutting processing previously,whereby any finishing processing is not required after the shaping andthe sliding bearing can be obtained cheaply.

According to the invention, the sliding bearing having suitable axialwidth with the positions to which loads are applied like claim 1 can bemanufactured.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] FIG. 1 is a sectional view of a sliding bearing according tothis embodiment.

[FIG. 2] FIG. 2 is a development of a half bearing along a peripheraldirection.

[FIG. 3] FIG. 3 is a sectional view of a flat-plate member.

[FIG. 4] FIG. 4 is a sectional view of a first pressing means performingrough bending.

[FIG. 5] FIG. 5 is a sectional view of a second pressing meansperforming finish bending.

[FIG. 6] FIG. 6 is a diagram of results of an experiment.

[FIG. 7] FIG. 7 is a diagram of results of an experiment.

[FIG. 8] FIG. 8 is a diagram of results of the experiments.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment shown in the drawings is explained FIG. 1 is a sectionalview of an essential part of an engine and shows a crankshaft 2 which ispivoted rotatably concerning a cylinder block 1 and a sliding bearing 3which pivots the crankshaft 2 to the cylinder block 1.

A semicircular recess in which an upper side in the drawing of thesliding bearing 3 is housed is formed in the cylinder block 1, and a cap4 in which a semicircular recess fixing the sliding bearing 3 to thecylinder block 1 is fixed to a lower part of the cylinder block 1 withbolts (not shown).

The sliding bearing 3 includes a pair of upper and lower semicircularhalf bearings 11 and 12 and is configured cylindrically by engagingperipheral ends of the half bearings 11 and 12 with each other.

A back plate made by metal such as stainless steel is formed in an outerperipheral surface of each of the half bearings 11 and 12. A slidingsurface layer made by metal such as aluminum is laminated on an innerperipheral surface of the back plate (see FIG. 3), and fine slots areformed peripherally in a surface of the sliding surface layer.

In the sliding bearing 3, an oil supply hole 11 a (when an oil groove isfirmed along a peripheral direction, from the oil supply hole 11 a viathe oil groove) which is communicated with an oil supply path 1 a formedin the cylinder block 1 is formed in the half bearing 11 of the side ofthe cylinder block 1, and lubricating oil is supplied via the oil supplyhole 11 a to a space between the sliding bearing 3 and the crankshaft 2.

FIG. 2 is a drawing of the half bearing 12 of the side of the capdeveloped along a peripheral direction for explanation. Since the halfbearing 11 of the side of the cylinder block 1 has substantially thesame configuration as the half bearing 12 of the side of the cap 4,detailed explanation of the half bearing 11 is omitted.

As shown in FIG. 2, in the half bearing 12 of the sliding bearing 3 inthis embodiment, widths of both peripheral ends 12 a and a central part12 b are small and a width of quarter part 12 c positioned therebetweenis large. For example, the width of the quarter part 12 c is larger thanwidths of the peripheral ends 12 a and the central part 12 b about 300to 400 μm.

Both axial end surfaces 12 d of the half bearing 12 are finished withcutting processing by a manufacturing method explained below. Namely, inthis embodiment, the width of the half bearing 12 in an axial directionis uneven and the axial end surfaces of the half bearing 12 arefinished.

Furthermore, a chamfered shape 12 e (see FIG. 3) is formed in each ofinner and outer peripheral surfaces of the half bearing 12.

The half bearings 11 and 12 configured as the above are combined and theengine is equipped with the sliding bearing 3 as shown in FIG. 1,whereby below effect can be obtained.

Firstly, a connecting rod whose tip is provided thereon with a piston ispivoted on the crankshaft 2 of the engine, and when explosion occurs ina combustion chamber hole in which the piston is housed, pressure of theexplosion is applied to the crankshaft 2 via the piston and theconnecting rod.

Large load generated by the explosion is applied to a contact surfacewith the sliding bearing 3 via the crankshaft 2. The large load isapplied especially to the quarter part 12 c of the half bearing 12 atthe side of the cap 4.

Then, it is necessary that a connection range of the quarter part 12 cwith the crankshaft 2 is set large and an oil film between thecrankshaft 2 and the sliding bearing 3 is secured so as to bear thelarge load.

On the other hand, the large load as the above is not applied to theperipheral ends 12 a and the central part 12 b of the half bearing 12,whereby sliding resistance between these parts and the crankshaft 2 ispreferably reduced.

However, in the conventional half bearing, since the width in the axialdirection is fixed, the widths of the peripheral ends and the centralpart must be set large corresponding to the width of the quarter part towhich the large load is applied, whereby the sliding resistance of theperipheral ends and the central part is increased and fuel efficiency isworsened.

On the other hand, according to the sliding bearing 3 of thisembodiment, the width of the quarter part 12 c to which the large loadis applied is large and the widths of the peripheral ends 12 a and thecentral part 12 b are small, whereby the sliding resistance can bereduced at the part to which the large load is not applied whilesecuring enough oil film at the part to which the large load is applied.

Next, an explanation will be given on the manufacturing method of thesliding bearing 3 having the above configuration.

Firstly, a long and narrow material wound coil-like is suppliedintermittently by a predetermined length at a time, and the long andnarrow material is cut along a direction perpendicularly a lengthwisedirection thereof, whereby a flat-plate material 21 which is strip-likeshaped is obtained.

Subsequently, as shown in FIG. 3, end surfaces of four sides of theflat-plate material 21 are cut, parts which are made into the axial endsurfaces 12 d and the peripheral end surfaces 12 a are finished when theflat-plate material 21 is made into the half bearing 12.

At the time of the cutting processing of the flat-plate material 21,slant surfaces are formed at positions at the side of inner and outerperipheral surfaces of the half bearing 12 when the flat-plate material21 is shaped into the half bearing 12, whereby the slant surfaces aremade into the chamfered shapes 12 e of the inner and outer peripheralsurfaces of the half bearing 12 when the flat-plate material 21 is madeinto the half bearing 12.

By cutting the end surfaces of the flat-plate material 21 as the above,in the manufacturing method of the sliding bearing 3 according to thepresent invention, it is not necessary to cut the axial end surfaces ofthe half bearing 12 after the flat-plate material 21 is shaped into thehalf bearing 12, whereby cost of the processing can be reduced incomparison with the conventional manufacturing method that axial endsurfaces of a material shaped semicircular are cut.

After the flat-plate material 21 is obtained as the above, rough bendingthat the flat-plate material is pressure-deformed into a semicircularmaterial 22 with a first pressing means 23 shown in FIG. 4 is performed.

The first pressing means 23 includes a lower mold 23 a in which a recessis formed and an upper mold 23 b which presses the flat-plate material21 downward so as to pinch it with the lower mold 23 a and deform itinto the semicircular material 22.

The first pressing means 23 does not compress both peripheral endsurfaces 22 a of the semicircular material 22 to be shaped and onlydeforms the flat-plate material 21 semicircular.

After obtaining the semicircular material 22 with the rough bending asthe above, finish bending of the semicircular material 22 is performedwith a second pressing means 24 shown in FIG. 5.

The second pressing means 24 includes a lower mold 24 a in which arecess housing the semicircular material 22 is formed, and an upper mold24 b which presses the peripheral end surfaces 22 a of the semicircularmaterial 22 along the peripheral direction thereof.

In the finish bending process, by pressing the peripheral end surfaces22 a of the semicircular material 22 with the upper mold 24 b, so-calledcoining is performed so as to maintain the semicircular material 22 at afixed shape.

Subsequently, by cutting the inner peripheral surface of thesemicircular material 22 obtained by the above process, the slidingsurface layer with the crankshaft 2 is finished, whereby the halfbearing 12 is obtained.

At this time, as mentioned above, the axial end surfaces 12 d and theperipheral end surfaces 12 a of the half bearing 12 are not cut.

When the flat-plate material 21 is shaped semicircular with the firstpressing means and the second pressing means, the width of the quarterpart 12 c of the half bearing 12 is longer than the widths of theperipheral ends 12 a and the central part 12 b by extension of thematerial or the like, whereby the half bearing 12 mentioned above can beobtained.

Since the axial end surfaces 12 d are finished previously by the cuttingprocessing before the above shaping, the half bearing 12 whose width inthe axial direction is not uniform can be manufactured easily.

FIGS. 6 to 8 show results of experiments concerning the sliding bearing3 according to this embodiment, and comparative experiments of the halfbearing 12 obtained by the manufacturing method according to the presentinvention (invention) with the half bearing of the conventionalmanufacturing method, that is, the half bearing whose axial end surfacesare cut and finished after deforming the flat-plate materialsemicircular (conventional product).

FIG. 6 is measurement of straightness of a rear surface at the side ofthe outer peripheral surface of the half bearing 12 of each of theinvention and the conventional product. The straightness is measured atpositions of 20°, 90° (the central part 12 b) and 160° along the axialdirection of the half bearing 12 concerning the center of the halfbearing 12.

According to the results of the experiment, it is found that theinvention has better straightness than the conventional product. That isguessed that the axial end surfaces are cut after the semicirculardeformation in the conventional product, whereby internal stressaccumulated in the material deformed semicircular is released and causesthe bad straightness.

When the straightness of the rear surface of the half bearing 12 isgood, adhesion with the cylinder block 1 and the cap 4 is improved andsludge and the like are prevented from entering a space therebetween,whereby load resistant is improved as shown by below results of theexperiments.

FIG. 7 shows results of fatigue tests concerning reciprocating load ofthe invention and the conventional product. Two samples of theconventional product and three samples of the invention are tested.

As conditions of the experiment, instead of the crankshaft, a rotationshaft is pivoted by the sliding bearing 3 and rotated at 3000 rpm.Surface pressure of 57 MPa is applied intermittently from the rotationshaft to the sliding bearing 3 while temperature at the side of the rearsurface of the sliding bearing 3 is maintained at 170° C. Then, numberof repetition until the sliding bearing 3 is broken by fatigue ismeasured.

According to the results of the experiment, it is understood that thenumber of repetition of the invention is higher than that of theconventional product, whereby fatigue resistance of the invention ishigher than that of the conventional product.

FIG. 8 shows correlation of the straightness of the rear surface of thesliding bearing 3 and the fatigue resistance of the sliding bearing 3concerning the reciprocating load according to the result of themeasurement of FIG. 6 and the result of the experiment of FIG. 7. Avertical axis shows the number of repetition until the fatigue occurs,and a horizontal axis shows the straightness of the rear surface of theperipheral central part 12 b of the sample.

According to FIG. 8, it is understood that the sliding bearing 3 havingthe good straightness of the rear surface shows the higher fatigueresistance than the sliding bearing 3 having the bad straightness.

In the invention, the axial end surfaces 12 d are finished previously bythe cutting processing before the flat-plate material 21 is deformedsemicircular, and any cutting processing is not performed after thedeformation, whereby the sliding bearing 3 having the good straightnessof the rear surface can be obtained easily.

On the other hand, the flat-plate material is shaped semicircular andthen the axial end surfaces are cut as the conventional product, wherebythe straightness of the rear surface is worsened and the fatigueresistance is worsened.

If the half bearing 12 whose width is changed with the positions isshaped semicircular and then the axial end surfaces 12 d are obtained bythe cutting processing conventionally, this cutting processing isdifficult and the cost is increased.

INDUSTRIAL APPLICABILITY

According to the present invention, a sliding bearing having suitablewidths with positions to which loads are applied can be obtained,thereby being useful industrially.

1. (canceled)
 2. A manufacturing method of a sliding bearing, whereinflat-plate materials are deformed semicircular so as to manufacturesemicircular half bearings, and both peripheral ends of the halfbearings are contacted to each other so as to shape these memberscylindrically, characterized in that parts of the flat-plate materialswhich are to be both axial end surfaces and both peripheral end surfacesof the half bearings after the deformation are finished by cuttingprocessing previously, and subsequently, the flat-plate materials aredeformed semicircular so as to manufacture the half bearings.
 3. Themanufacturing method of the sliding bearing according to claim 2,wherein at the time of finishing the end surfaces of the flat-platematerials, slant surfaces are formed at positions to be at sides ofinner peripheral surfaces of the half bearings after finishing, and theslant surfaces are made into chamfered shapes of the inner peripheralsurfaces of the half bearings.
 4. The manufacturing method of thesliding bearing according to claim 2, wherein at the time of deformingthe flat-plate material semicircular, rough bending that the flat-platematerial is pressed and deformed semicircular is performed, andsubsequently, finishing bending that end surfaces of both peripheralends of the semicircular material obtained by the rough bending arepressed is performed.